Estimating AC Mitigation Requirements for PipelinesInstalled in High Voltage AC Corridors: Fault Conditions

摘要

A previous paper paper1 has addressed the question of estimating mitigation requirements for pipelines installed inrnhigh voltage AC corridors, such as to maintain induced voltages at acceptable levels during normal operatingrnconditions on the power system. This paper addresses the more difficult problem of estimating what mitigation isrnrequired to maintain pipeline coating stress voltages within acceptable limits during fault conditions on the powerrnsystem. The difficulty of this undertaking arises primarily from the fact that AC interference during faultrnconditions includes not only induction, but also voltages transferred through earth to the pipeline location fromrnpower line poles or towers near which the fault has occurred: as a result, the analysis is more complex and thernmitigation requirements are influenced by a greater number of factors. Furthermore, since the goal is to minimizernthe voltage difference between the earth and the pipeline steel, the interaction between the earth and barernmitigation wire buried next to the pipeline and connected thereto must be considered. This paper shows howrnfactors such as soil resistivity, soil layering, length of parallelism, proximity of pipeline to transmission line, faultrncurrent levels, transmission line static wire type, transmission line structure grounding and coating resistancerndetermine mitigation requirements.